The invention concerns a ballet shoe suitable for steps executed with the weight of the body supported by the toe (for which the term of the art is the French word "pointe").
A ballet shoe primarily comprises a sole to which is joined a flexible cap or "upper", usually made from cotton or satin, which covers the front of the foot and extends on either side of the instep to run around behind the heel. The front of the upper is made rigid by a box or "vamp" adapted to surround the front part of the foot; in practise the vamp is formed of glued together layers of cotton, jute and felt, for example, which are then formed to the required shape in the front part of the upper using a shoe tree or "last": the stiffness of the vamp depends of the nature and quantity of the glue. In practise the sole comprises an outer sole of leather, for example, and an inner sole extending as far as the end of the vamp formed by a leather or cardboard insole covered with cotton fabric and an underlying stiffener plate or "shank" of cardboard, for example.
Conventional ballet shoes of this kind have enabled generations of dancers to execute the gracious "pointe" dance steps required by their art but at the cost of painful compression of the front part of the foot causing the infamous "dancer's bunion" and sometimes pathology of the bones, ligaments, muscles or tendons.
It must be remembered that in "pointe" dance steps all of the contact force with the floor passes through the front part of the foot (especially the toes) which must not deflect forwards, backwards or sideways. These forces can be extremely high and experiments have shown that under certain conditions, when executing "pointe" jumps on concrete, for example, accelerations in the order of -10 g can be generated in the front part of the foot. This explains the need for the vamp to support the front part of the foot very firmly if serious accidents are to be avoided.
A ballet shoe is in practise inevitably deformed from its new state of maximum stiffness as it is worn in and its stiffness deteriorates until it must be replaced; because of this, for most of the time for which it is used a shoe causes painful compression of the front part of the dancer's foot and reducing this painful period (for example by using a reduced quantity of glue) shortens the useful life of the shoe.